Speed-control system



March 27, 1928. 1,664,134

L. SCHOMBOURGER ET AL SPEED CONTROL SYSTEM Filed May a, 1925 2Sheets-Sheet l FigL March 27, 1928. 1,664,134

L. SCHOMBOURGER ET AL SPEED CONTROL SYSTEM Filed May 6. 1925 2Shets-Sheet 2 Fig.2

Invenrors: Lucien Schornbourger, H'Ldde Kfiohrage, y

Their Akrorneg.

Patented 27,1928. 1,664,134 UNITED STATES PATENT OFFICE.

LUCIEN SCHOMBOURGER AND HIDDE K. SCHRAGE, OF PARIS, FRANCE, ASSIGNORS TOGENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK. A

SPEED-CONTROL SYSTEM.

Application med m a, 1925, Serial No. 23,474, and in France July 1,1924.

Our invention relates to systems wherein it may be replaced by atransformer having the speed of an induction motor is controlledconductively independent primary and seeby variation in the magnitude ofa regulatondary windings. The exciting machine or ing voltage applied toits secondary circuit frequency changer 11 comprises an arn'iatnrethrough a regulating machine, and has for winding 12 which is connectedto the excit- 60 its object the provision of an improved an ing fieldwinding 8 of the regulating marangement whereby stability of the motorchine 5 through brushes 13 and field windmaintained under differentconditions of op ings 14. eration. It will be readily. understood that,when 10 In the operation of speed control systems the machine 11 has thesame number of poles 6 comprising a regulating machine concateand isoperated at the same speed as the innated with an induction motor,ditficulty is duction motor 1, the frequency of the current encountereddue to variation in phase relatr:-n1smitted between machine 11 and fieldtion between the field flux of the regulating winding 8 of machine 5 isthesame as that 15 machine and the secondary voltage of the of the motorsecondary currentand that the 7 motor produced by change in the ohmicand n'iagnitude of the current thus supplied to inductive voltage dropsof the regulating the winding 8 may be regulated by adjustmachine fieldcircuit. In accordance with ment of the transformer our invention, thisdifficulty is avoided by In order to render the current of the windtheprovision of an exciting machine deing 8 indepedent of the slipfrequency and signed to neutralize the effect of these ohmic load of themotor 1, it is necessary that comand inductive voltage drops underdifferent ponent voltages be produced for neutralizconditions ofoperation. ing or balancing its ohmic and inductive Our invention willbe better understood drops. The ohmic drop of the winding 8 is from thefollowing description when considof course directly proportional to themagni- 80 cred in connection with the accompanying tude of its excitingcurrent while its indrawing and its scope will be pointed out in ductivedrop is proportional to the product the appended claims. of themagnitude and frequei'icy of this cur- Referring to the drawing, Fig. 1shows a rent. In accordance with our invenion, the speed control systemwherein means comfrequency changer 11 is so designed that a 8.5 prisingan exciting machine are provided voTtageequal to the ohmic drop of thewindfor controlling the phase of the regulating ing 8 is producedthrough the winding 12 voltage impressed on the motor secondary while avoltage equal to the inductive drop circuit; and Fig. 2 shows a modifiedar- Of the winding 8 is produced through the rangement for controllingthe regulating windings 14.. The manner in which these on voltage.component voltages are produced will be Fig. 1 shows an induction motor1 which readily understood when it is considered is arranged to besupplied with current from that the flux and Voltage of the Winding 12 apolyphase line 2 through leads 3 and is are determined by the adjustmentof the arranged to have its secondary circuit contransformer 9 whichcontrols the current of nected to the armature circuit 4 of a regulatthewinding 8 and that the voltage produced ing machine 5 through slip rings6 and the through the windings 14 is dependent both compensating fieldwindings 7 of the ma on the flux of the winding 12 and the rate at chine5. The regulating machine 5 is prowhich this flux moves through space.With 45 vided with a polyphase field winding 8 conthe proper relationthus established between nected to the polyphase line 2 through a pothewindings 8, 12 and 14, the current of tential regulating transformer 9,a current winding 8 is independent of the motor load transformer 10having its primary windi and slip frequency and the stability of theconnected in the leads 3, and an exciter masystem under differentconditions of operachine 11 having its rotor mounted on the tion i en urshaft of the induction motor 1. While the WVith the transformer 9connected as transformer 9 is shown as an auto-transshown in Fig. 1,unity power factor operaformer having its primary windings contion ofthe motor will be obtained for all nected in star and its secondarywindings speeds at one motor load. At other loads connected in delta, itwill be apparent that approximate control of the power factor andcompounding ot thci motor speed may be attained by use of the currenttransformer which modifies the current supplied to the machine 11 in.accordance withthc motor load.

Fig. 2 shows a speed control system which difi ers from that previouslydescribed in that the regulating machine field winding 8 is connectedbetween the brushes 1?) and 13 of two frequency cl'iangers 11 and 11which are similar to the machine 11 of Fig. 1 are mounted on the shaftof: the motor 1., and are arranged to have thci' arn'iature windings '12and; 12 respectively supplied with current from the polyphase line 2through a transformer 9 and slip rings 15.

In the operation of the arrangement shown by Fig. 2, the magnitude ofthe regu lating voltage produced through the machine 5 is varied bymoving the brushes 13 and 13' through equal angles in oppositedirections and the power "factor at which current is utilized by themotor 1 is controlled by moving the brushes 13 and 13 through unequalangles in opposite directions. It will be apparent that any suit-ablemeans may be provided for adjusting the positioni of the brushes. As inthe case of the an rangemeut shown by Fig. 1. the excitation of themachine 5 is independent of the motor load and slip frequency.

The embodiments of the invention illustrated and described hereinhave'been selected for the purpose of clearly setting forth theprinciples involved. It will be apparent, however, that theinventionii's susceptible of being modified in many ways tomeetthediii'erent conditions encountered in its use and we therefore aimto cover by the appended claims all the modifications within the truespirit and scope of our invention.

hat we claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. The combination of an induction motor a regulating machine providedwith an eX- citing winding and. concatenated with said motor forcontrolling the speed thereof, an exciter for said exciting windingincluding series connected arniaturc and held windings for controllingthe excitation ot the exciting winding of the regulating machine, saideXciter armature and iield windings being related to cause the n'odiudion oi component voltages whereby the ohmic and inductive drop in saidexciting winding are neutralized.

2. The combination of an induction motor a regulating machine providedwith an exciting field winding and concatenated with said motor forcontrolling the speed thereof, and a pair of exciting machinesconiprising armature windings connected to opposite cues of saidexciting winding through series field windings, said armature and seriesiicld windings being so proportioned as to cause the production ofcomponent voltages whereby the ohmic and inductive drops of saidexciting fieldwiuding a re neutralized.

3. The combination of an induction motor, a regulating machine providedwith an exciting field winding and concatenated. with said motor forcontrolling the speed thereof, a source of current, and a pair ofexciting machines comprising armature windings connected to said sourcethrough slip rings and to opposite ends of said exciting field windingthrough adjustable brushes and series field windings, the turns of saidarma ture and series field windings being so related as to cause theproduct-ion of component voltages whereby the ohmic and inductive dropsof said exciting field winding are neutralized.

In witness whereoih we have hereunto set our hands this 9th day ofAprih1925.

LUGIEN sonoiieomienn. HIDDE K. SOH'RAGE.

